building failures foundations

BUILDING FAILURESFAILURES IN FOUNDATIONS• Foundation settlement cracking due to differential settlement

of the wall footings, poor original construction, water, nearby blasting operations

• Concentrated loads or point loads and their characteristic appearance as foundation damage

Excessive backfill height; premature backfill causing foundation buckling, leaning, or collapse Improper materials (soft brick, below grade) causing settlement, differential settlement, leaning, or tipping of foundation walls Shallow/absent/undermined/cut footings, settlement & frost damage causing settlement, differential settlement, leaning, or tipping of foundation walls. Interior cracks in buildings may be traced to foundation movement or damage Shrinkage cracks: in concrete, concrete block, are usually not a structural concern, but are a possible point of water or radon entry

BUILDING FAILURESFAILURES IN FOUNDATIONS

Improper soil preparation - failure to compact soils, especially where foundations are constructed on fill, can lead to settling footings & slabs Foundation damaged during moved/modular building set, often impact damage General Signs of Foundation Movement or Foundation Damage Foundation cracksFoundation Leaning or Tipping Foundation Bulging Foundation Settlement, uniform or differential

Excessive loading leading to foundation fractures (frost heaves can produce similar damage)

BUILDING FAILURESFAILURES IN FOUNDATIONS-CRACKS

VERTICAL FOUNDATION CRACKS-

In masonry between two structures - differential settlement or thermal movement Straight or wandering, in poured concrete, generally even width, intermittent, or more often straight - shrinkage / thermal - low risk Straight generally even width, in a masonry block wall, in mortar joints but possibly right through concrete block - shrinkage / thermal - low to modest risk

SETTLEMENT CRACK


VERTICAL FOUNDATION CRACKS-

Straight or stepped in brick, esp. near ends of wall - expansion / thermal, potentially dangerous if wall bond courses are broken, collapse risk. In wall, wider at bottom than top - settlement under building. These cracks may be less serious than horizontal when found in a masonry block wall. These cracks could be quite serious when found in a brick wall, especially if bond courses are broken and there is risk of collapse.


• From corner towards adjacent opening, wider at top than bottom - often due to foundation settlement, expansive clay soil, frost damage, or damage from a shrub/tree close to the foundation wall.

• Under a ground floor window, from sill to ground, sill bowed up - often due to foundation heave, clay soil, frost, shallow or absent footings

In the foundation wall anywhere, wider at bottom than top - settlement under building

DIAGONAL FOUNDATION CRACKS - Diagonal & Step Crack Patterns in Building Foundations

SHRINKAGE CRACKS IF UNIFORM AND IRREGULAR IN DIRECTION


• Cold climates- frost, possible displacement inwards • Possible vehicle loading, displacement inwards

Horizontal Foundation Cracks Located High on a Foundation Wall

Horizontal Foundation Cracks Located at Mid-wall Height on a Foundation• Masonry block or stone walls which are cracked and/or bulging

inwards at mid height on the wall are likely to have been damaged by vehicle traffic or earth loading

Horizontal Foundation Cracks Located Low on a Foundation Wall• Earth Loading, especially if in an area of dense or wet soils • Horizontal dislocation of a masonry block or brick wall may appear

first as a crack and then later as horizontal movement as a wall is pushed inwards by earth or wet soil pressure.


• A settlement crack is more likely to be wider at top than its bottom as the foundation "bends" over a single point, allowing differential settlement; it is possible for a settlement crack to appear fairly uniform however if a foundation breaks vertically and then pursues differential settlement.

• Settlement cracks need to be separated into initial settlement due to construction or site factors and ongoing settlement due to site factors

Usually wider at top, usually continuous, may be multiple!Imaginary line, right angle to diagonal crack, usually = direction of downwards movement; may indicate upwards wall-lift - see if settlement cracks at opposite end of wall (e.g. in FL) Multiple cracks of either type may occur in a given area. Usually visible both outside and inside if material is exposed.

Foundation Settlement: crack patterns

BUILDING FAILURESFAILURES IN FOUNDATIONS-by material

CONCRETE-Concrete shrinkage cracks• Characteristic discontinuous path, and are not structural cracks

Not usually a structural problem but may in some cases permits water leakage through the foundation wall.

This is characteristic of concrete (or mud) shrinking while giving up its moisture.

Concrete cracks often occur at natural stress points where the uniformity of a poured concrete wall or floor has been interrupted by placement of a window (in walls of course) or inside corners (in floors). You may often find shrinkage cracks that trace across the concrete to these stress points


CONCRETE-Holes and penetrations in concrete foundations:

Poorly-sealed openings left for piping for water or electrical lines or where form ties were broken off may form points of water entry into the structure but are not normally a structural concern.


CONCRETE-Concrete foundation settlement cracking:

If cracks noted and documented after this time continue to increase in length or width, some other cause is at work and further investigation is needed.

In this case the movement to uneven footing settlement was aggravated by the combination of having placed the footing partly on bedrock, water from roof and surface spillage and runoff causing soil settlement (the contractor had not compacted the backfill under the footings), and by ongoing foundation blasting at a neighboring lot.


STONE-

Stone walls, like other masonry walls, are often damaged by water and frost, especially where roof spillage splashes close to the foundation wall.

Stone foundation walls on pre-1900 buildings are often quite thick, up to four feet at their base. In their original design these walls tolerated water in the outside soils by permitting it to seep through the wall and often to drain away through a dirt floor or even a through-wall drain in a low corner. Such dry-laid structural stone foundation walls rarely fail by leaning but are often found bulged or damaged by water, frost, vehicle traffic, or by modification by the building owner.


STONE-

• Dislocations and loose stones, commonly at building walls and corners above grade where exposed to splashing roof runoff.

Bulges : due to frost, water, vehicle loading if vehicles are driven close to walls

Cracks (if mortared): settlement, vehicle driving close to walls Interruptions and loss of integrity such as where stones have been removed from a structural wall to add a door or to provide access for mechanicals


STONE-

• Water leakage is very common with all stone walls, especially dry-laid stones which were placed without use of mortar. In original use such walls were often expected to be leaky and provision was made for water passing through the wall to continue across a sloped (dirt) floor and out of the basement or crawl space


BRICK-

• Cracks and Bulges in brick foundation walls: frost and earth loading - can push a below-grade brick foundation wall inwards. Often the wall is bulged inwards into a basement or crawl area as well as showing horizontal and step cracking and loose bricks over the bulged area. Damage occurs from slightly above ground level to roughly the frost line


BRICK-

• Diagonal or Stair-Stepped Cracks and loose bricks in walls: these brick wall crack patterns are typically due to frost, settlement, sometimes thermal expansion (Thermal Expansion Cracking of Brick), usually diagonal or stair-stepped, often at building corners where roof spillage is concentrated.

Also shows that the upper section of the wall has bulged outwards past the lower or right hand section of this structure.damaged by water (roof spillage) and frost

http://www.inspectapedia.com/structure/FoundationOccur6.htm


General Suggestions for the Evaluation of Foundation CracksLinks at page left discuss the evaluation of individual types of

building foundation cracks. Here are some general suggestions:Look at shape, pattern, frequency of occurrence, relationship to wall discontinuities and angles, placement of wall penetrations,

correlation with cracks in floors, and location in the wall (corners, center), as well as length, width, continuity, age of wall, relation to

site conditions (depth of backfill, blasting, rock).Shrinkage cracks are usually uniform in width or (less common)

vee-shaped, wider at top and diminishing or stopping before reaching the bottom of the foundation wall (where attachment to

footing may tend to hold foundation wall materials in place). A wall crack which continues into the floor is likely to involve the building

footings and may be a settlement crack of more structural importance.

are needed to decide what repair may be needed.


General Suggestions for the Evaluation of Foundation CracksLinks at page left discuss the evaluation of individual types of

building foundation cracks. Here are some general suggestions:Look at shape, pattern, frequency of occurrence, relationship to wall discontinuities and angles, placement of wall penetrations,

correlation with cracks in floors, and location in the wall (corners, center), as well as length, width, continuity, age of wall, relation to

site conditions (depth of backfill, blasting, rock).Shrinkage cracks are usually uniform in width or (less common)

vee-shaped, wider at top and diminishing or stopping before reaching the bottom of the foundation wall (where attachment to

footing may tend to hold foundation wall materials in place). A wall crack which continues into the floor is likely to involve the

building footings and may be a settlement crack of more structural importance.

Concrete shrinks as it cures. In poured concrete, shrinkage cracks may be non-uniform if wall components are held by

footings/framing; very often there are minor shrinkage cracks which are hairline, random, intermittent, multiple, and

meandering in the concrete, forming discontinuous cracks in the wall. Shrinkage cracks occur as concrete cures, appearing more

frequently and larger if the mix was improper and where control joints were omitted. Omission or pattern of placement of steel

reinforcement may also be a factor in crack formation and location.

Poured concrete shrinkage cracks: usually shrinkage cracking is due to conditions at original construction: poor mix, rapid curing,

possibly other conditions. Shrinkage cracks are less likely to require structural monitoring and repair in poured concrete as

they would be expected to continue after initial curing.Concrete block foundation walls shrink as they cure. They rarely

expand much on exposure to moisture and temperature variations. In concrete block walls shrinkage cracks are likely to be

uniform in width and usually occur towards the center of a concrete masonry unit (CMU) wall. The wall is stronger at the

building corners.Brick walls do not normally shrink, but rather, grow indefinitely. Bricks are not often used for below-grade foundations but were

often used above-grade supporting the first floor of older buildings, and of course entire buildings may be constructed using structural brick walls (look for the bond courses). If you see a crack in a brick wall it's more likely due to movement in the structure, a

support problem, or due to thermal expansion. Cracks in structural brick walls may be very serious if the bond courses are broken as there is then a risk of sudden catastrophic wall collapse. Cracks

and especially bulged cracked brick walls need immediate expert investigation.

Stone foundation walls do not normally crack through individual stones, but the interlaced stone layout of the wall may be bulged

and cracked due to damage from frost, loading from driving vehicles near the wall, or by the removal of stones to pass piping

or make doorways. As with other cases of foundation movement, a diagnosis of the cause, amount of movement, and effects on structure are needed to decide what repair may be needed.

building failures foundations

Documents

foundation heave

foundation damage excessive

footings slabs foundation

settlement frost damage

causing foundation buckling

damage shrinkage cracks

wall footings

interior cracks